Stator of motor having insulation structure for separation of stator winding groups

ABSTRACT

Disclosed is a stator of an EPS motor, the stator including a stator core including a plurality of teeth protrusively formed toward a center of an inner circumferential surface, a plurality of coils wound on the teeth at a predetermined counts, an insulator coupled to an upper surface and a bottom surface of the stator core to insulate the coil from the stator core, and an insulation tube situated nearest to a coil wound on an adjacent stator core and inserted into a coil wound on an outmost side of the teeth.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit under 35 U.S.C. §119 of KoreanPatent Application Nos. 10-2011-0081030, filed Aug. 16, 2011,10-2011-0081033, filed Aug. 16, 2011, 10-2011-0081039, filed Aug. 16,2011 and 10-2011-0085339, filed Aug. 25, 2011, which are herebyincorporated by reference in their entirety.

BACKGROUND

1. Field of the Invention

The present disclosure relates to a stator of a motor.

2. Discussion of the Related Art

Generally, almost every vehicle employs an electric power-assiststeering system. Such an electric power-assist steering system generatesan assist force based on the steering torque and the steering angle, soas to enhance the steering performance of the vehicle.

That is, a steering system that assists a steering force of a vehiclewith a separate power is used to enhance the motion stability of avehicle.

Conventionally, the auxiliary steering device uses hydraulic pressure,but an Electronic Power Steering (EPS) system adapted to transmit arotation output of an electric motor to a steering shaft via a speedreduction mechanism has been increasingly employed these days from aviewpoint of a reduction in engine load, a reduction in weight, anenhanced steering stability and a quick restoring force.

The EPS system is such that an Electronic Control Unit (ECU) drives amotor in response to steering conditions detected by a speed sensor, atorque angle sensor and a torque sensor to enhance a steering stabilityand provide a quick restoring force, whereby a driver can safely steer avehicle.

The EPS system is also such that a motor assists a torque manipulating asteering wheel to allow a driver to steer a vehicle with less power,where the motor employs a Brushless Direct Current (BLDC) motor.

The BLDC motors have been increasingly used because the brushless motorsare excellent in maintenance property, have a small size, and arecapable of generating a high torque. The BLDC motor generally forms anexterior look by coupling of a housing and a cover member, an innercircumferential surface of the housing is provided with a stator, andthe stator is centrally formed with a rotor rotatably mounted inelectrical interaction with the stator. The rotor is rotatably supportedby a rotation shaft, and an upper surface of the rotation shaft isconnected by a steering shaft of a vehicle to provide a power assistingthe steering of the vehicle as mentioned above.

Meanwhile, a coil wound on teeth of split cores forming a stator core isvery tightly arranged, such that winding of coils needs a considerablymeticulous engineering process lest a short-circuit be generated that iscaused by close-contact among the coils wound on each tooth. However,there may occur a problem of generating a defect on the product due tofailure by an operator in the process of assembly because a distancebetween coils wound on the teeth is too close or tight.

It is, therefore, desirable to overcome the above problems and others byproviding an improved stator of a motor.

BRIEF SUMMARY

This section provides a general summary of the disclosure, and is not acomprehensive disclosure of its full scope or all of its features.

The present disclosure is directed to cope with the abovementionedproblems/disadvantages and it is an object of the present disclosure toprovide a stator of a motor improved in an insulation structure amongcoils to inhibit short-circuit caused by interference among coils woundon teeth of adjacent split cores from occurring.

Technical problems to be solved by the present disclosure are notrestricted to the abovementioned description, and any other technicalproblems not mentioned so far will be clearly appreciated from thefollowing description by the skilled in the art.

In a general aspect of the present disclosure, there is provided astator of an EPS motor, the stator comprising: a stator core including aplurality of teeth protrusively formed toward a center of an innercircumferential surface; a plurality of coils wound on the teeth at apredetermined counts; an insulator coupled to an upper surface and abottom surface of the stator core to insulate the coil from the statorcore; and an insulation tube situated nearest to a coil wound on anadjacent stator core and inserted into a coil wound on an outmost sideof the teeth

Preferably, but not necessarily, the insulation tube has a thicknesssmaller than a gap among the plurality of coils wound on the statorcore.

Preferably, but not necessarily, the insulation tube has a lengthcorresponding to a length of a surface opposite to an adjacent coil ofthe stator core.

Preferably, but not necessarily, the insulation tube is provided with asynthetic resin material having a diameter corresponding to a diameterof the coil.

Preferably, but not necessarily, one insulation tube is inserted intoeach coil wound on the teeth.

In another general aspect of the present disclosure, there is provided astator of an EPS motor, the stator comprising: a stator core including aplurality of teeth protrusively formed toward a center of an innercircumferential surface; a plurality of coils wound on the teeth at apredetermined counts; an insulator coupled to an upper surface and abottom surface of the stator core to insulate the coil from the statorcore; and an insulation plate extensively formed from any one lateralwall surface of the insulator to inhibit the plurality of adjacent coilsfrom being short-circuited.

Preferably, but not necessarily, the stator core forms a circular shapecoupled by a plurality of split cores each having a tooth, and theinsulator includes upper and bottom insulators provided in a symmetricalstructure in a shape corresponding to that of the split core to wrap theteeth and an inner circumferential surface of the split core from upperand bottom sides.

Preferably, but not necessarily, the upper and bottom insulators includean insulator body wound on a periphery of the coil and having a toothgroove at an inner surface into which the teeth are inserted, and aguide plate protrusively formed from the insulator body at apredetermined height to inhibit the coil wound on the insulator bodyfrom being disengaged.

Preferably, but not necessarily, the insulation plate has a thicknesssmaller than a gap among the plurality of coils wound on the statorcore.

Preferably, but not necessarily, the insulation plate has a lengthcorresponding to a length of the insulator body wound by the coil.

Preferably, but not necessarily, the insulation plate isinjection-molded along with the insulator in the same resin material asthat of the insulator.

Preferably, but not necessarily, the insulation plate is rotatablyformed at a lateral wall of the insulator.

In still another general aspect of the present disclosure, there isprovided a stator of an EPS motor, the stator comprising: a stator coreincluding a plurality of teeth protrusively formed toward a center of aninner circumferential surface; a plurality of coils wound on the teethat a predetermined counts; a bus bar coupled to an upper surface of thestator core to be conductibly connected to the coil; and an insulationplate extensively formed from a bottom surface of the bus bar to beinserted into a space unit formed by the plurality of coils when thestator core and the bus bar are coupled, to inhibit adjacent coils frombeing short-circuited.

Preferably, but not necessarily, the insulation plate has a thicknesssmaller than a gap among the plurality of coils wound on the statorcore.

Preferably, but not necessarily, the insulation plate has a lengthcorresponding to a length of the stator core.

Preferably, but not necessarily, the insulation plate isinjection-molded along with the bus bar in the same resin material asthat of the bus bar.

Preferably, but not necessarily, the insulation plates is provided inthe number corresponding to that of the coils wound on the stator core.

In still another general aspect of the present disclosure, there isprovided a stator of an EPS motor, the stator comprising: a stator coilcoupled to a cylindrically shaped motor housing; a plurality of coilswound on an inner side of the stator core; and an insulation paper soarranged as to wrap an outside of the plurality of coils, wherein theinsulation paper is bent in the shape of a ‘

’ to be inserted into a bottom lateral surface of the stator coreopposite to a floor surface of the motor housing.

Preferably, but not necessarily, the insulation paper wraps an exteriorof a portion of the plurality of coils.

Preferably, but not necessarily, a coil adjacent to a coil wrapped bythe insulation paper is not arranged with the insulation paper.

Preferably, but not necessarily, the portion wrapped by the insulationpaper is brought into contact with a floor surface of the motor housing.

Preferably, but not necessarily, both distal ends of the insulationpaper face toward an opened surface side of the motor housing.

The stator of an EPS motor according to the present disclosure has anadvantageous effect in that an erroneous operation such as motorshort-circuit caused by coil interference can be inhibited, becauseinterference among coils wound on teeth of split core is ruled out byinsulation plate.

Another advantage is that a bus bar is integrally provided with aninsulation plate to rule out interference among wound coils the momentthe bus bar and a stator core are assembled to dispense with a separateinsulation process including a separate winding of coils on theinsulation plate.

Still another advantage is that the insulation paper is bent in theshape of a ‘

’ to face a floor surface of a motor housing into which a stator core isinsertedly coupled, whereby a separate disengagement device is dispensedwith.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the present disclosure and are incorporated in thepresent disclosure and constitute a part of this application, andtogether with the description, serve to explain the principle of thedisclosure. In the drawings:

FIG. 1 is a schematic perspective view of a stator core according to anexemplary embodiment of the present disclosure;

FIG. 2 is an exploded perspective view of a split core and an insulator,essential parts of FIG. 1, according to a first exemplary embodiment ofthe present disclosure;

FIG. 3 is a schematic view illustrating a state in which a coil insertedby an insulation tube, which is an essential part of FIG. 1, is wound ona split core according to the present disclosure;

FIG. 4 is a plan view of FIG. 1;

FIG. 5 is an exploded view illustrating a split core and an insulator,which are essential parts of FIG. 1 according to a second exemplaryembodiment of the present disclosure;

FIG. 6 is a schematic view illustrating a state in which a coil is woundon an insulator integrally formed with an insulation plate, which is anessential part of FIG. 5, according to the present disclosure;

FIG. 7 is an exploded perspective view of an insulation plate and astator core according to a third exemplary embodiment of the presentdisclosure;

FIG. 8 is a schematic view illustrating an assembled state of theinsulation plate and the stator core of FIG. 7;

FIG. 9 is an enlarged view of ‘A’ part of FIG. 8;

FIG. 10 is an exploded perspective view of an insulation paper and astator core according to a fourth exemplary embodiment of the presentdisclosure;

FIGS. 11 and 12 are schematic view illustrating an assembled state ofthe insulation paper and the stator core of FIG. 10; and

FIG. 13 is a cross-sectional view illustrating a coupled state of astator to a motor housing according to an exemplary embodiment of thepresent disclosure.

DETAILED DESCRIPTION

Advantages and features of the present invention may be understood morereadily by reference to the following detailed description of exemplaryembodiments and the accompanying drawings. Detailed descriptions ofwell-known functions, configurations or constructions are omitted forbrevity and clarity so as not to obscure the description of the presentdisclosure with unnecessary detail. Thus, the present disclosure is notlimited to the exemplary embodiments which will be described below, butmay be implemented in other forms. In the drawings, the width, length,thickness, etc. of components may be exaggerated or reduced for the sakeof convenience. Furthermore, throughout the descriptions, the samereference numerals will be assigned to the same elements in theexplanations of the figures, and explanations that duplicate one anotherwill be omitted.

Accordingly, the meaning of specific terms or words used in thespecification and claims should not be limited to the literal orcommonly employed sense, but should be construed or may be different inaccordance with the intention of a user or an operator and customaryusages. Therefore, the definition of the specific terms or words shouldbe based on the contents across the specification. The terms “a” and“an” herein do not denote a limitation of quantity, but rather denotethe presence of at least one of the referenced item.

As may be used herein, the terms “substantially” and “approximately”provide an industry-accepted tolerance for its corresponding term and/orrelativity between items. Such an industry-accepted tolerance rangesfrom less than one percent to ten percent and corresponds to, but is notlimited to, component values, angles, et cetera.

Now, a stator of EPS motor according to a first exemplary embodiment ofthe present disclosure will be described in detail with reference toFIGS. 1, 2 and 3.

FIG. 1 is a schematic perspective view of a stator core according to anexemplary embodiment of the present disclosure, FIG. 2 is an explodedperspective view of a split core and an insulator, essential parts ofFIG. 1, according to a first exemplary embodiment of the presentdisclosure, and FIG. 3 is a schematic view illustrating a state in whicha coil inserted by an insulation tube, which is an essential part ofFIG. 1, is wound on a split core according to the present disclosure.

Generally, a stator core (100) configured as shown in FIG. 1 includes aplurality of split cores (101) illustrated in FIG. 2, where theplurality of split cores (101) includes teeth (102) protrusively formedtoward a center of the stator core (100). The teeth (102) are tightlywound by a coil (110). The split cores (101) wound by the coil (110) areassembled to a circumferential direction to form a cylindrical statorcore (100) as shown in FIG. 1.

Meanwhile, upper and bottom sides of the split cores (101) areinsertedly coupled by an insulator (120) for insulation, where a shapeof the insulator (120) preferably corresponds to a cross-section of eachsplit core (101). FIG. 2 is an exploded perspective view illustrating astate in which the insulator (120) is inserted into upper and bottomsides of the split cores (101), and FIG. 3 is a schematic viewillustrating a state in which the coil (110) is wound on the split core(101) coupled with the insulator (120) according to the presentdisclosure.

The insulator (120) is formed with a synthetic resin material excellentin insulation property and is preferably injection-molded using a mold.The insulators (120) are respectively inserted into the upper and bottomsides of the split cores (101) forming the stator core (100) tocompletely encompass the teeth (102) of the split cores (101). Thus, thecoil (110) can be wound while the teeth (102) of the split core (101)and the insulator (120) are divided. At this time, the insulators (120)respectively assembled to the upper and bottom sides are verticallysymmetric.

An insulation tube (200) is insertedly coupled to the coil (110), andprovided in a pipe shape having a diameter corresponding to the coil(110). The insulation tube (200) is provided with an insulatingsynthetic resin material used for wire coating, and the insulatingsynthetic resin material is preferably resistant to high temperature.

According to the exemplary embodiment of the present disclosure, alength of the insulation tube (200) is shorter than that of the statorcore (100). In a case the length of the insulation tube (200) is toolong, chances are a connection section with a coil terminal (not shown)of the coil (110) is insulated. Thus, the length of the insulation tube(200) preferably corresponds to a length of a surface faced by adjacentcoils (110).

The insulation tube (200) is not inserted into an entire area of woundcoil (110), but inserted to one strand of the outmost coil (110) of thewound coil (110), as shown in FIGS. 3 and 4.

That is, as illustrated in FIG. 4, the coil (110) wound on the splitcore (101) is such that distances to coils (110) wound on the adjacentsplit cores (101) are not same, where the distance is narrow at somesections and distances are wide at some sections. Thus, in view of thefact that interference between the wound coils (110) is caused by anarrow distance in the coils (110), a problem caused by short-circuit inthe coils (110) can be inhibited if the coils (110) wound thereon areinsulated.

Meanwhile, thickness of the insulation tube (200) is smaller than adistance of facing surfaces in the plurality of coils (110), whereby thecoils (110) wound on the adjacent split cores (101) are inhibited frombeing excessively too close with the insulation tube (200) when thesplit cores (101) are assembled. This is because if the thickness of theinsulation tube (200) is greater than a gap between the coils (110),there may be generated an interference with a coil (110 a, see FIG. 4)wound nearest to the coil (110) inserted into the insulation tube (200)to make it difficult to assemble the stator core (100), in a case thesplit core (101) wound with the coil (110) is assembled.

Furthermore, as shown in FIG. 4, the insulation tube (200) is providedto rule out any interference with the nearest coil (110 a) wound on theadjacent split core (101), and in case of each coil (110) wound on eachtooth (102), only one insulation tube (200) is inserted into the coil(110). For example, in case of stator core (100) formed by coupling of atotal of 12 split cores, the number of teeth of the coils (110) wound onthe teeth of the split core (101) is 12. At this time, a total of 12insulation tubes (200) are preferably provided to be inserted into theoutmost one coil of respective coils (110).

According to the present disclosure thus described, in view of the factthat coils (110) wound inside the stator core (100) are insulated byadjacent coils (110) and the insulation tube (200) to inhibit generationof short-circuit caused by contact between the coils (110), such that itis possible to reduce the management cost through reduced managementlevel of winding process over that of the prior art.

Now, a second exemplary embodiment of the present disclosure will bedescribed with reference to FIGS. 5 and 6.

FIG. 5 is an exploded view illustrating a split core and an insulator,which are essential parts of FIG. 1 according to a second exemplaryembodiment of the present disclosure, FIG. 6 is a schematic viewillustrating a state in which a coil is wound on an insulator integrallyformed with an insulation plate, which is an essential part of FIG. 5,according to the present disclosure.

Generally, a stator core (100) includes therein a plurality of teeth,where the plurality of teeth (not shown) is protrusively formed toward acenter of the stator core (100). Each tooth is tightly wound by a coil(110). In order to wind the coils (110), the state core (100) includes aplurality of split cores (101) (see FIG. 5), and the split cores areassembled with coils being wound to form a cylindrical stator core(100).

Meanwhile, upper and bottom sides of the split cores (101) areinsertedly coupled by the insulator (120) for insulation. FIG. 5 is anexploded perspective view illustrating a state where the insulator (120)is inserted into the upper and bottom sides of the split core (101), andFIG. 6 is a schematic view illustrating a state where the split core(101) is wound by the coil (110).

The insulator (120) is formed with upper and bottom insulators (120 a,120 b), where the upper and bottom insulators (120 a, 120 b) preferablytake a vertical symmetrical shape to encompass the teeth and an innercircumferential surface of the split core (101) from upper and bottomsides. The upper and bottom insulators (120 a, 120 b) include aninsulator body (121) and a guide plate (122).

The stator core (101) including a first spilt core and a second spiltcore adjacently disposed to the first spilt core. The upper insulator(120 a) includes an upper base portion (1201) disposed on an uppersurface of the tooth (102) of the first spilt core, and an upperexpansion portion (1202) extensively formed from the upper base portion(1201) towards a center portion of the tooth (102) of the first spiltcore and disposed on a lateral surface of the tooth (102) of the firstspilt core. The bottom insulator (120 b) includes a bottom base portion(1206) disposed on a bottom surface of the tooth (102) of the firstspilt core, and a bottom expansion portion (1207) extensively formedfrom the bottom base portion (1206) towards the center portion of thetooth (102) of the first spilt core and disposed on a lateral surface ofthe tooth (102) of the first spilt core. An upper insulation plate(1203) is extensively formed from one side end portion of the upperexpansion portion (1202), and a bottom insulation plate (1208) isextensively formed from the bottom expansion portion (1207).

The insulator body (121) is provided to encompass the teeth and an innercircumferential surface of the split core (101) and is also providedwith an insulating resin material. As illustrated in FIG. 5, theinsulator body (121) is preferably formed therein with a tooth groove(123) encompassing the teeth. A length of the insulator body (121) ispreferably half the length of the split core (101). A periphery of theinsulator body (121) thus configured is wound by the coil (110) as shownin FIG. 6.

The guide plate (122) is preferably protruded from the insulator body(121) at a predetermined height to inhibit the coil wound on theinsulator body (121) from being disengaged. Meanwhile, a surfaceopposite to the wound coil (110), which is a lateral surface of theinsulator (120), is formed with an insulation plate (200) extended froma lateral surface of the insulator body (121).

Generally, the insulator (120) is formed with a synthetic resin materialexcellent in insulation property, and the insulation plate (200) ispreferably formed with the same material as that of the insulator (120).To this end, the insulator (120) and the insulation plate (200) arepreferably injection-molded at the same time using a mold.

Referring to FIGS. 5 and 6, the insulation plate (200) is provided at alateral wall surface of the insulator (120) in a plate shape having apredetermined area to face a lateral exposed surface of the coil (110)wound on the stator core (100). Thus, a surface arranged with theinsulation plate (200) is not exposed with the coil (110).

According to the second exemplary embodiment of the present disclosure,a length of the insulation plate (200) is shorter than a length of theinsulator body (121) forming the insulator (120). This is because theinsulator (120) formed with the insulation plate (200) is divisivelycoupled to upper and bottom sides of the split core (101) forming thestator core (100). Preferably, the insulation plate (200) is provided tooccupy an approximate half of the length of the coil (110).

Furthermore, as illustrated in FIGS. 5 and 6, the insulation plate (200)is provided to correspond to a width of the coil (110) wound on thestator core (100) to cover a gap between each facing surface of theplurality of wound coils (110).

Preferably, the insulation plate (200) is formed only at one lateralsurface of the insulator (120). This is because in case of the statorcore (100) formed by coupling of the split cores (101), if theinsulation plate (200) is formed only at one side, insulation can beprovided by the insulation plate (200) provided at the adjacent splitcore (101) side even if the coil (110) wound on the split core (101)arranged at an opposite position is exposed.

Meanwhile, the insulation plate (200) may be formed with a littlethinner at a connection area to rotate at a predetermined angle relativeto the insulator (120), or may be formed with a groove.

According to the abovementioned configuration, a winding process of thecoil (110) can be maximally and easily performed by unfolding theinsulation plate (200) to the maximum during winding of the coil (110),and in a case the winding process of the coil (110) is finished, theinsulation plate (200) can be closed to cover the wound coil (110).

Meanwhile, thickness of the insulation plate (200) is smaller than adistance of opposite surfaces in the plurality of wound coils to inhibitthe coils (110) wound on the adjacent split coils (101) from interferingwith the insulation plate (200) when the split cores (101) areassembled. In a case the thickness of the insulation plate (200) isthicker than the gap between the coils (110), the assembly process ofthe stator core (100) may become difficult due to interference with thecoils (101).

Furthermore, the insulation plate (200) is intended to rule outinterference of all the adjacent coils (110) and is preferably providedin the number corresponding to the number of wound coils (110). Forexample, in case of the stator core (100) formed by coupling of a totalof 12 split cores, the number of coils (110) wound on the teeth of thesplit cores is 12. At this time, a total of 12 insulation plates may beprovided to be inserted into an entire space in respective coils.

According to the present disclosure thus configured, the coils (110)wound inside the stator core (100) is insulated from the adjacent coils(110) by the insulation plate (200) to inhibit generation ofshort-circuit caused by contact among coils (110), whereby it ispossible to reduce the management cost through reduced management levelof winding process over that of the prior art.

FIGS. 7, 8 and 9 illustrate a stator of an EPS motor according to athird exemplary embodiment of the present disclosure.

That is, the stator core (100) includes therein a plurality of teeth(not shown), where the plurality of teeth is protrusively formed towarda center of the stator core (100). Each tooth is tightly wound by a coil(110). In order to wind the coils (110), the state core (100) includes aplurality of split cores, and the split cores are assembled with coilsbeing wound to form a cylindrical stator core (100).

Meanwhile, FIG. 7 illustrates a process in which the insulation plate(200) is inserted into the stator core (100) wound with the coils. Theinsulation plate (200) is formed with an insulating material and isintegrally formed with the bus bar (120) coupled to an upper side of thestator core (100).

The bus bar (120) serves to provide an electric power to each of thecoils (110) wound on the stator core (100) and is provided in anapproximately ring shape. The bus bar (120) is protrusively formed to acircumferential direction with a terminal (121) conductibly connected tocoil terminals (111) each provided at a distal end of the coil (110).

As illustrated in FIG. 7, the insulation plate (200) is provided on afloor surface of the bus bar (120) in a plate shape having apredetermined length and is protrusively formed at a predeterminedlength toward the floor surface coupled by the stator core (100).Furthermore, the insulation plate (200) is preferably formed with thesame resin material as that of the bus bar (120). To this end, theinsulation plate (200) and the bus bar (120) are preferablyinjection-molded at the same time using a mold during mold-forming ofthe bus bar (120).

According to the exemplary embodiment of the present disclosure, alength of the insulation plate (200) preferably corresponds to a lengthof the stator core (100), and is at least longer than a length of thewound coil (110), but should not exceed the length of the stator core(100).

Referring to FIGS. 8 and 9, the insulation plate (200) is provided tocorrespond to a width of the coil (110) wound on the stator core (100),and inserted into a space formed between surfaces each facing theplurality of wound coils (110).

Meanwhile, as shown in FIG. 7, the insulation plate (200) is insertedinto the stator core (100) completed in coupling by all the coils (110)being wound, and in a case a thickness of the insulation plate (200) isthicker than a gap between the coils (110), the insertion process may bedifficult due to interference among the coils (110). Thus, the thicknessof the insulation plate (200) is smaller than a distance of facingsurfaces among the plurality of wound coils (110), whereby the insertionof the insulation plate (200) to the wound coils (110) is not interferedduring insertion of the insulation plate (200).

Meanwhile, the insulation plate (200) functions to inhibit interferenceamong all the adjacent coils (110) and is preferably provided in thenumber corresponding to the number of wound coils (110). For example, incase of the stator core (100) formed by coupling of a total of 12 splitcores, the number of coils (110) wound on the teeth of the split coresis 12. At this time, a total of 12 insulation plates may be provided tobe inserted into an entire space in respective coils.

According to the present disclosure thus configured, the coils (110)wound inside the stator core (100) is insulated from the adjacent coils(110) by the insulation plate (200) to inhibit generation ofshort-circuit caused by contact among coils (110), whereby it ispossible to reduce the management cost through reduced management levelof winding process over that of the prior art.

FIG. 10 is an exploded perspective view of an insulation paper and astator core according to a fourth exemplary embodiment of the presentdisclosure, FIGS. 11 and 12 are schematic view illustrating an assembledstate of the insulation paper and the stator core of FIG. 10, and FIG.13 is a cross-sectional view illustrating a coupled state of a stator toa motor housing according to an exemplary embodiment of the presentdisclosure.

Generally, a stator core (100) includes therein a plurality of teeth,where the plurality of teeth (not shown) is protrusively formed toward acenter of the stator core (100). Each tooth is tightly wound by a coil(110). In order to wind the coils (110), the state core (100) includes aplurality of split cores (101), and the split cores are assembled withcoils being wound to form a cylindrical stator core (100).

FIG. 10 is a schematic view illustrating a procss where an insulationpaper (200) is inserted into the stator core (100) wound with coils. Asillustrated in FIG. 10, the insulation paper (200) used as an electricalinsulation material free from conductivity is manufactured by using amethod in which a synthetic resin having an insulation substance isincluded in fiber particles of paper, and a physical property of theinsulation paper (200) is of no big difference from the general paperbut is formed with a material excellent in insulation.

The insulation paper (200) is preferably bent in an approximate shape ofa ‘

’, and a floor surface of the insulation paper (200) is arranged on afloor surface of the stator core (100). That is, as shown in FIGS. 11and 12, the floor surface of the stator core (100) is arranged on thefloor surface of the insulation paper (200) to alternatively expose thecoil (110), while an upper surface of the stator core (100) protrusivelyformed by the coil terminals (111) connected to the coil (110) exposesall the wound coils.

According to the coupling relation thus configured, as shown in FIG. 13,the floor surface of the bent insulation paper (200) is brought into atight and close contact with a floor surface (11) of the motor housing(10) when the closed floor surface (11) of the motor housing (10) isinsertedly coupled by the floor surface of the stator core (100). Then,the insulation paper (200) is never disengaged, even if no separatedisengagement inhibition device is provided, unless the insulation paper(200) be forcibly pulled out through an opening (12) of the motorhousing (10).

Meanwhile, as shown in FIG. 10, the insulation paper (200) may beinserted into the stator core (100) completed in coupling by all thecoils (110) being wound, but, in this case, the insertion process of theinsulation paper (200) may not be easy due to interference among theadjacent coils (110). Thus, a process of winding the insulation paper(200) may be pre-performed in the processes of winding the coils (110)on the split cores to allow the insulation paper (200) to encompass aperiphery of the coil (110), and the split cores may be assembled toform the stator core (100).

Furthermore, according to the exemplary embodiment of the presentdisclosure, although the insulation paper (200) may be so arranged as toencompass the periphery of all the coils (110), but in consideration ofthe fact that an object of the insulation paper (200) is to inhibitinterference of the adjacent coils (110), there is no need of anarrangement in which the insulation paper (200) encompasses theperiphery of all the coils (110).

That is, as shown in FIGS. 11 and 12, in a case the insulation paper(200) is inserted into one coil (110) to encompass the periphery of thecoil (110), there is no need of inserted arrangement of the insulationpaper (200) on the coils (110) arranged at a vicinity of the coil (110)encompassing the periphery by the insulation paper (200).

For example, in case of the stator core (100) formed by coupling of atotal of 12 split cores, the number of coils (110) wound on the teeth ofthe split core is 12. At this time, a total of six insulation paper(200) can be arranged. FIGS. 11 and 12 are schematic views illustratingan arrangement state in which a coil (110) wrapped by the insulationpaper (200) and a coil (110) not wrapped by the insulation paper (200)are alternatively arranged.

As apparent from the foregoing, the stator of EPS motor has anindustrial applicability in that the coils (110) wound inside the statorcore (100) is insulated from the adjacent coils (110) by the insulationpaper (200) to inhibit generation of short-circuit caused by contactamong coils (110), whereby it is possible to reduce the management costthrough reduced management level of winding process over that of theprior art.

Although embodiments have been described with reference to a number ofillustrative embodiments thereof, it should be understood that numerousother modifications and embodiments can be devised by those skilled inthe art that will fall within the spirit and scope of the principles ofthis disclosure. More particularly, various variations and modificationsare possible in the component parts and/or arrangements of the subjectcombination arrangement within the scope of the disclosure, the drawingsand the appended claims.

What is claimed is:
 1. A stator of an EPS motor, the stator comprising:a stator core including a first spilt core and a second spilt coreadjacently disposed to the first spilt core; a coil unit including afirst coil wound on a tooth of the first spilt core and a second coilwound on a tooth of the second spilt core; an insulator coupled to thestator core to insulate the coil unit from the stator core; and aninsulation plate extensively formed from the insulator and disposedbetween the first coil of the coil unit and the second coil to inhibitthe first coil from coming into contact with the second coil and causinga short circuit; wherein the insulator comprises an upper insulator anda lower insulator; wherein the upper insulator includes an upper baseportion disposed on an upper surface of the tooth of the first spiltcore, and an upper expansion portion extensively formed from the upperbase portion towards a center portion of the tooth of the first spiltcore and disposed on a lateral surface of the tooth of the first spiltcore; wherein the bottom insulator includes a bottom base portiondisposed on a bottom surface of the tooth of the first spilt core, and abottom expansion portion extensively formed from the bottom base portiontowards the center portion of the tooth of the first spilt core anddisposed on a lateral surface of the tooth of the first spilt core;wherein the insulation plate includes an upper insulation plateextensively formed from the upper expansion portion, and a bottominsulation plate extensively formed from the bottom expansion portion;wherein a first end of the insulation plate is rotatable formed at oneside distal end of a first side lateral wall of the insulator, and asecond end opposite to the first end of the insulation plate is formedas a free end; wherein a width from the first end of the insulationplate to the second end of the insulation plate corresponds to adistance between the one side distal end of the first side lateral wallof the insulator and the other side distal end of the first side lateralwall of the insulator; wherein the insulation plate has a fixedthickness from the first end to second end; and wherein the insulationlate is not symmetric about an imaginary line connecting a center of theEPS motor and a center of the insulator.
 2. The stator of claim 1,wherein the insulation plate has a thickness smaller than a gap betweenthe first coil and the second coil.
 3. The stator of claim 1, whereinthe upper base portion, the upper expansion portion, and the upperinsulation plate are integrally formed.
 4. The stator of claim 1,wherein the insulation plate is rotatably formed at a lateral wall ofeach of the upper expansion portion and the bottom expansion portion. 5.The stator of claim 1, wherein the upper insulator and the bottominsulator are provided in a symmetrical shape.
 6. The stator of claim 1,wherein a length of each of the upper expansion portion and the bottomexpansion portion is half a length of the tooth of the first spilt core.7. The stator of claim 6, wherein the insulation plate has a lengthcorresponding to a length of each of the upper expansion portion and thebottom expansion portion.
 8. The stator of claim 1, wherein theinsulator further comprises a second side lateral wall opposite to thefirst side lateral wall in a circumferential direction, and wherein theinsulation plate is disposed at the first side lateral wall of theinsulator, and the insulation plate is not disposed at the second sidelateral wall of the insulator.